Methods for manufacturing single wall carbon nanotubes are now well known to those skilled in the art. See for example U.S. Pat. Nos. 6,333,016; 6,919,064; 6,962,892 and 7,459,138, the entirety of each identified patent being incorporated herein by reference.
Due to their structure, single wall carbon nanotubes have remarkable optical and electrical properties, high strength, as well as thermal and chemical stability. As a result, industry is continuously finding new uses for single wall carbon nanotubes including but not limited to printed electronic circuits and touch screen interfaces.
However, in order to achieve the full potential of this unique substance, the single wall carbon nanotubes must be provided in substantially pure condition. The typical manufacturing process for single wall carbon nanotubes relies upon metal catalysts supported on particles of alumina, magnesium oxide or silica or combinations thereof. Following growth and termination of the single wall carbon nanotube, the catalyst particle remains attached to the resulting nanotube structure. Removal of the metal component in a manner that does not damage or degrade the tube sidewall is desirable to provide a pure single wall carbon nanotube. Additionally, provision of a single wall carbon nanotube that is open on both ends of the tube is desirable to enhance the pore volume and surface area of the tube for certain applications, such as gas separation or water desalination membranes, super-capacitors, lithium ion batteries, etc.